我的正则表达式验证密码有什么问题？

Question

这是我验证密码的模式：

$pattern = '/^[0-9A-Za-z!@#$^%*_|;:\'"`~.,\(\)\{\}\[\]\<\>\\\/\?\-\+\=\&]{6,}$/m';

我使用函数preg_match 来验证

preg_match($pattern, $string);

但是当我运行它时，它显示了这个错误： Warning: preg_match(): Unknown modifier '\' in xxx on line 13

我的正则表达式有什么问题？

这里是正则表达式的解释：http://regex101.com/r/rR6uH0/

^ assert position at start of a line
[0-9A-Za-z!@#$^%*_|;:'"`~.,\(\)\{\}\[\]\<\>\\\/\?\-\+\=\&]{6,} match a single character present in the list below
Quantifier: Between 6 and unlimited times, as many times as possible, giving back as needed [greedy]
0-9 a single character in the range between 0 and 9
A-Z a single character in the range between A and Z (case sensitive)
a-z a single character in the range between a and z (case sensitive)
!@#$^%*_|;:'"`~., a single character in the list !@#$^%*_|;:'"`~., literally
\( matches the character ( literally
\) matches the character ) literally
\{ matches the character { literally
\} matches the character } literally
\[ matches the character [ literally
\] matches the character ] literally
\< matches the character < literally
\> matches the character > literally
\\ matches the character \ literally
\/ matches the character / literally
\? matches the character ? literally
\- matches the character - literally
\+ matches the character + literally
\= matches the character = literally
\& matches the character & literally
$ assert position at end of a line
g modifier: global. All matches (don't return on first match)
m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)

Answer 1

您需要两次转义正斜杠。有时您需要转义双斜杠的原因是它们被剥离了两次——一次由 PHP 引擎（在编译时），一次由正则表达式引擎。

来自PHP manual：

单引号和双引号 PHP 字符串具有反斜杠的特殊含义。因此，如果 \ 必须与正则表达式 \ 匹配，则 PHP 代码中必须使用 "\\" 或 '\\'。

更新后的正则表达式应如下所示：

$pattern = '/^[0-9A-Za-z!@#$^%*_|;:\'"`~.,\(\)\{\}\[\]\<\>\\\\\/\?\-\+\=\&]{6,}$/m';